Hydraulic valve lifter leak-down tester



April 1, 1953 F. c. BURRELL 2,635,464

HYDRAULIC VALVE LIFTER LEAK-DOWN TESTER Filed Feb. 23, 1949 2 Sl-IEETS-SHEET l Snnemo:

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HYDRAULIC VALVE LIFTER LEAK-DOWN TESTER Filed Feb. 25, 1949 2 SHEETS-SHEET 2 lllnnl 3rmentor J52 ava/Z Patented Apr. 21, 1953 HYDRAULIC VALVE LIFTER LEAK-DOWN TESTER Frank C. Burrell, Detroit, Mich, assignor to General Motors Corporation, Detroit, Mich., a corporation of Delaware Application February 23, 1949, Serial No. 77,955 8 Claims. (01. 73-119) This invention relates to testing equipment and particularly to a tool for testing automatic takeup devices such as hydraulic valve lifters or tappets. My tool is particularly adapted for measuring the leak-down rate of hydraulic valve tappets while installed in the engine.

The principal object of the invention is to providesuch a tool having a spacer element or feeler insertable between adjacent normally abutting elements of the valve train to effect a temporary elongation of the latter and resultant displacement of the valve from its seat against the action of its valve spring, together with means automatically effective to signal the completion of sufficient leak-down in the tappet to compensate for said elongation.

Another object of the invention is to provide a tool adapted for single-hand operation in manually lifting a valve operating follower from its cam, automatically inserting a spacer element therebetween and automatically effecting its withdrawal therefrom upon subsequent reseating of the valve.

Further objects of the invention relate to the hereinafter described structure and arrangement of elements making up the preferred embodiments of my invention as illustrated in the accompanying drawings, in which:

Figure 1 is a perspective view of one form of my tool particularly adapted for testing hydraulic valve lifters in an L head type engine.

Figure 2 is an enlarged fragmentary sectional view taken on line '22 of Figure 1.

Figure 3 is a fragmentary view of my tool of Figure 1 together with portions of an L head engine, showing their relationship during measurement of a hydraulic tappet for rate of leakdown. u

Figure 4 is an enlarged fragmentary v1ew similar to Figure 3 but showing the parts in their relative positions just prior to beginning a leakdown rate check.

Figure 5 is a fragmentary plan view taken substantially on the line 5-5 of Figure 4.

Figure 6 is a view similar to Figure 5 but showing the parts in their relative positions at the start of a leak-down rate check.

Figure 7 is an elevational view of another form of my tool shown in operation in an overhead valve type engine.

Figure 8 is an enlarged perspective view of the tool of Figure 7.

Referring first to Figures 1 and 2 which illustrate one embodiment of my tool, there is shown an elongated member in the form of a rod I having a bent portion 2 at one end which serves as a handle and terminating at its opposite or forward end in a relatively thin and wide section or nose 3. successively rearward of the nose 3 is an abutment in the form of an upstanding pin 4, a journal 5 and a second abutment in the form of staking 6 (Figure 3). Mounted respectively fore and aft of each other on the journal 5 are a carrier member in the form of a sleeve 1 and a compression coil spring 8, the latter reacting against the abutment 6 to bias the sleeve 1 forwardly against the pin 4. Flat washers 9 and 0 may be provided at opposite ends of the spring 8. To effectively lock it rotatively to the journal 5 when in its normal or forwardmost position thereon, the sleeve 1 is provided at its front end with a notch H for engagement with the pin 4. The side l2 of notch II is flared as shown, for a purpose to be later explained.

Fixed to the sleeve I as by threaded fastenings l5 and I6 clamping them between lateral extensions l1 and I8 thereof are a blade-like spacer element or thickness feeler in the form of a plate [9 and one leg 2!] of a generally triangular shaped cantilever leaf spring 2|. Plate [9 extends parallel with the axis of sleeve 1, and when the latter is in its normal or forwardmost position (Figures 1 and 3) on the journal 5, the plate [9 extends a substantial distance forwardly of the front end of the nose 3, as shown. Leaf spring 2| is designed to have a lower load-deflection rate than the coil spring 8, andincludes resiliently displaceable legs 22 and 23 which are disposed in a plane normal to the plane of the plate [9 and parallel with the longitudinal axis thereof. The forward end of the fixed leg 20 of this spring is turned upward around the front end of the sleeve extension I? to provide a stop 24 for limiting rearward displacement of the lower or forward end 25 of its leg 22, the normal or free position of which is substantially forward of stop 24 as shown in Figure 1.

The manner of applying the tool just described to measure the leak-down rate of a hydraulic valve tappet in an L head automotive type engine is illustrated in Figures 3, 4, 5 and 6. In such engines the valve operating camshaft 30 conventionally has a reduced diameter section 3| adjacent each cam 32, and the follower 33 overhangs the latter on both sides, as indicated in outline in Figures 5 and 6. In the particular engine shown, the follower 33 forms the lower end of the cylinder 34 of a hydraulic valve lifter or tappet 35 which is slidably reciprocable in a guide 36 provided therefor in the frame 31 3 of the engine. The piston 38 of the tappet rides on a column of fluid such as oil within the cylinder 34 and has its upper end 39 abutting the stem 40 of its associated engine valve (not shown), which is biased to closed position by a valve spring 4|, all in a well-known manner.

Since the tappet 35 must be capable of contracting end-Wise to compensate for linear expansions of the valve train under conditions of rising operating temperatures and thus permit the valve to fully close during idle periods of the cam 32, a certain minimum amount of leak-down of the tappet piston 38 relative to its cylinder 34 must occur when a load tending to fore-shorten them is applied. A high rate of leak-down is unsatisfactory since it results in excessive working of the parts of the tappet, and decreases the amount the valve operated thereby is opened. Hence, for proper functioning in the engine, each tappet must operate within certain desired maximum and minimum leak-down limits.

In making a tappet leak-down test the operator holds the tool by the handle 2, with the leaf spring 2| projecting upwardly, and locates the forward edge of the plate l9 as far forwardly as possible opposite the abutting surfaces of the follower 33 and cam 32. Then by applying force in a forward direction with the handle 2, he causes the rod to slide forwardly in the sleeve 1 against the biasing action of the coil spring 8 until the nose 3 is inserted between the adjacent reduced diameter section 3| of the camshaft and the follower 33, the relative positions of the parts at this point being as shown in Figures 4 and 5. The pin 4 being clear of the notch l in the forward end of the sleeve 1 in this position, the handle 2 is then turned to effect a tilting (Figure 6) of the nose 3 sufficient to lift the follower 33 from the cam 32 and concurrently displace the valve from its seat in opposition to the valve spring 4|. When the follower has been thus lifted an amount sufllcient to provide clearance between it and the cam 32 for the plate IS, the latter is automatically projected forwardly with the sleeve 1 by the pressure of the coil spring 8 to the position shown in Figure 6signaling the start of the leak-down test. Leg 22 of the leaf spring 2|, which is also carried forwardly by the movement of the sleeve 1, is deflected by the follower 33 until its lower end 25 moves into contact with the stop 24, which latter then serves to prevent further forward movement of the sleeve 1 toward the engine. As will be noted from Figure 6, the sleeve 1 at this point has not fully returned to its normal position on the journal 5, i. e. to where the pin 4 engages the notch however, upon subsequently relieving the manual force applied to the handle 2, the coil spring 8 will move the rod rearwardly to the position shown in Figure 3, in which the pin 4 bottoms in the notch and the nose 3 is withdrawn clear of the camshaft 30. The flared side l2 of the notch l serves to guide the re-entry of the pin 4 thereinto during this last mentioned movement.

The compression of the valve spring 4| as the result of the valve being temporarily displaced from its seat provides sufficient clamping pressure to retain the plate I 9 in its inserted position between the cam 32 and follower 33, notwithstanding the biasing action of the leaf spring 2| tending to withdraw it therefrom. This same valve spring pressure also forces the piston 35 further inward in the tappet cylinder 34, at a rate depending on the leak-down characteristics of the tappet being tested. After sufficient leakdown has occurred therein, the valve returns to its seat, relieving the clamping pressure of the valve spring 4|, whereupon the leaf spring automatically withdraws the plate |9signaling the end of the leak-down test. By timing the interval between the insertion and withdrawal of the plate l9 and comparing the same with the results of like tests on the other tappets in the engine, a ready check is obtained of the leak-down characteristics.

A simpler form of the tool embodying most of the features of my invention is shown in Figure 8. This tool may be used in place of that previously described and differs therefrom principally in the omission of the means for manually displacing the valve from its seat and automatically inserting the spacer element. The tool of Figure 8 comprises a simple bar or handle 50, adjacent the forward end of which is secured the plate I9 and triangular shaped spring 2| as by screws 5|. The operation of this tool for measuring the leakdown rate of a hydraulic valve tappet in an overhead valve engine 52 is illustrated in Figure 7. After first manually displacing the valve stem 53 downwardly from its rocker arm 54, the plate I9 is inserted between the latter and the upper end of the stem 53. This displacement may be affected in various ways such as by inserting a screw driver or like tool (not shown) between the valve spring washer 55 and the rocker arm 54 and prying them apart. The leg 22 of the leaf spring 2| is adapted to engage the side of the valve spring washer 55 in resisting the insertion of the plate l9, and upon completion of leak-down of the hydraulic valve tappet and reseating of the valve the spring 2| automatically effects the withdrawal of the plate IS in the same manner as previously described in the case of the L head engine.

I claim:

1. A tool of the class described, comprising an elongated member having a handle at one end and a cam follower lifting nose at its opposite end, a spacer carrier slidable longitudinally along a portion of the member and rotatable relative thereto, a spring mounted on the member and arranged to bias the carrier toward the nose, a spacer element of elongated relatively thin section fixed to the carrier, said spacer element being disposed laterally adjacent the nose and normally extending forwardly thereof, and a second spring carried by the carrier and arranged to engage a portion of the engine in opposition to insertion of the spacer element between the cam follower and its operating cam, said second spring having a lower load-deflection rate than the first named spring.

2. A tool for checking leak-down rates of hydraulic valve lifters in an engine having a camshaft with a section of reduced diameter adjacent each cam track and a cam follower associated with each cam track and overlying a portion of said reduced diameter section, comprising a, handie, a member extending forwardly therefrom and terminating in a relatively thin and wide nose insertable between a cam follower and a reduced diameter section of the camshaft, said member having a cylindrical bearing portion rearwardly of the nose portion, a sleeve of less length than the bearing portion and journaled for rotation and longitudinal movement thereon, an abutment rearwardly of the bearing portion, a first spring disposed between the abutment and the sleeve and adapted to bias the sleeve forwardly relative to the member, a second abutment at the forward end of the bearing portion for limiting forward movement of the sleeve relative to the member, said sleeve having a notch in its forward end engageable with the second abutment to rotatively lock the sleeve to the member when the sleeve is in its forwardmost position on the member, a blade-like element fixed to the sleeve for insertion between a cam follower and its associated cam track on the camshaft of the engine, said blade-like element extending parallel with the nose portion and terminating forwardly thereof in its normal position, a second spring fixed to the sleeve and adapted to engage a portion of the engine in opposing the insertion of the blade-like element, said second spring having a substantially lower load-deflection rate than the first spring.

3. In a tool of the class described, a relatively thin and fiat member f elongated section, a generally triangular shaped leaf spring having one of its triangular legs superimposed on and rigidly secured to said member adjacent one end thereof, the other two legs of the spring being disposed in a plane normal to the plane of the member and parallel with its longitudinal axis, the legs forming the angle nearest the opposite end of the member being unconnected to permit relative displacement between the different legs of the spring and accommodate insertion of said opposite end of the member between normally abutting elements of a valve train, said one leg of the spring having its end nearest said opposite end of the member turned up to form an abutment limiting the displacement of the spring leg adjacent thereto.

4. In a tool for use in checking a hydraulic valve lifter for leak-down rate while in place in an engine, a feeler member insertable in a valve train of the engine to effect a temporary spacing of the valve off its seat, and a resilient member mounted on the feeler member and having a portion suspended therefrom and adapted to engage a relatively fixed part of the engine and resiliently resisting the said insertion of the feeler member, said resilient member having sumcient stiffness to effect the withdrawal of the feeler member only upon the valve returning to its seat.

5. In a tool for checking the leak-down rate of hydraulic valve lifters while installed in the engine, a thickness feeler insertable in the valve train to effect a temporary spacing of the valve from its seat in opposition to the valve spring, and spring means resiliently resisting the insertion of the feeler and effective to withdraw it from the valve train upon reseating of the valve, said spring means being secured to the feeler and having a portion extending therefrom and adapted to engage a side of the valve spring during said insertion of the feeler.

6. In a tool for use in checking a hydraulic valve lifter for leak-down rate while in place in an engine, a feeler member insertable between the normally abutting surfaces of two elements of the engine valve train to effect a temporary spacing of the valve from its seat, and a resilient member having one end fixed to the feeler member and a freely suspended opposite end, said opposite end being adapted to engage one of said elements and resiliently resisting said insertion of the feeler member, said resilient member having sufficient stifiness to effect the withdrawal of the feeler member only upon the valve returning to its seat.

'7. A tool of the class described, comprising an elongated member terminating in a relatively thin and wide nose portion, a carrier slidable longitudinally on the member, resilient means on the member biasing the carrier toward the nose portion, a spacer element of elongated thin section fixed to the carrier and normally extending forwardly of said nose, and other resilient means mounted on the carrier and having a portion extending laterally thereof for engagement with the work, said other resilient means being yieldable to the biasing action of said first-named resilient means.

8. A tool for checking the leak-down rate of a hydraulic tappet in a valve train in which the valve is biased to seated position, comprising a member having an elongated portion terminating in a relatively thin and Wide end insertable between elements of the valve train to efiect a separation of normally abutting surfaces of said elements and consequent displacement of the valve from its seat, feeler means movably mounted on said portion for insertion between said surfaces while in said separated condition, resilient means carried by said member and urging said feeler means toward said end thereof, and other resilient means carried by said feeler means and engageable with a valve train associated element to oppose insertion of said feeler means between said surfaces.

FRANK C. BURRELL.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,779,812 Hastings Oct. 28, 1930 2,427,297 Modrey Sept. 9, 1947 2,454,159 Graves Nov. 16, 1948 

